This study was performed to determine the effects of the extracts of two alternative antimicrobial agents that do not harm the ecosystem (rosemary, Rosmarinus officinalis and aloe vera, Aloe barbadensis) when added to the feed of tilapia (Oreochromis niloticus) on the growth performance, proximate composition, and biometric characteristics. Rosemary extract was added to the experimental diet in ratios of 0.1%, 0.25%, and 0.5% while aloe vera extract was added to the experimental diet in ratios of 0.5%, 1%, and 2.5%. After 90 days of the feeding trial, no change was seen in the weight increase, specific growth rate, feed conversion ratio, condition factor, hepatosomatic index, or viscerosomatic index of the tilapia. The fact that proximate analyses did not differ between groups showed that the plant extracts did not adversely affect the health status of tilapia in the ratios used in this study. As a result, the addition of 0.1%, 0.25%, and 0.5% rosemary extract and the addition of 0.5%, 1%, and 2.5% aloe vera extract to tilapia feeds did not cause changes in the growth performance, biometric indexes, or chemical composition findings of the fish meat.

The hazardous effects of pesticides on various metabolic pathways are a great problem for environmental health and should be well determined. In the present study, the authors treated rainbow trout with 0.6 μg/L deltamethrin for 28 days and 1.6 mg/L 2,2-dichlorovinyl dimethyl phosphate for 21 days. After this time period, the authors observed alterations in mRNA expression levels of MT-A, MT-B and CYP-1A. Chronic exposure to low levels of pesticides may have a more significant effect on fish populations than acute poisoning. While both pesticides caused a significant increase on mRNA levels of MT-A and CYP-1A, MT-B mRNA levels were increased significantly only upon deltamethin administration. The significant increase in mRNA levels of the corresponding genes may be considered as a defence mechanism in addition to the antioxidants against oxidative stress, as well as a detoxification mechanism against adverse effects of pesticides.

No abstract

The river nerite (Theodoxus fluviatilis, Linnaeus, 1758) is one of the most common gastropod grazer species in Europe inland and brackish waters. Its feeding activity significantly impacts on periphyton which has a decisive role on the water parameters and the population dynamics. In the present study, reproductive outputs and larval phases of the river nerites were examined via field collected and laboratory cultivated samplings. The length of capsules laid by adults was between 0.7 and 1.1 mm. Viable embryos were detected first on the 33 rd day post-spawning. After few development phases embryo reached a ready-to-hatch phase with completely developed foot and pigmented protoconch before hatching. There was never more than one embryo per capsule. The earliest hatching was observed on the 53 rd day of spawning. But most of the embryos did not hatch even they were fully developed. The shell length of the hatchlings was about 0.8 and the width was 0.6 mm. It was estimated that the length of a newly hatched crawling juvenile can be about 1/7 of the length of an adult.

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